Background <p>The issue of school adaptation among urban adolescents has received increasing attention. Previous research has primarily focused on Chinese rural and mobile adolescents, exploring the impact of factors such as teacher support, resilience, and left-behind status on their academic achievement. However, there has been relatively limited research on urban adolescents in this regard.</p> Methods <p>In line with the study’s objectives, this study selected parent and student questionnaires from the CEPS (2013–2014) and CEPS (2014–2015) datasets for a matched analysis. This process resulted in a final sample of 2502 urban adolescents aged 13 to 15. The key variables examined included teacher academic support, teacher emotional support, teacher relationship support, resilience, school adaptation, and left-behind status. To investigate these relationships, we employed structural equation modeling to explore how resilience mediates the impact of teacher support on school adaptation among urban adolescents. Additionally, we examined whether left-behind status moderates this mediation process.</p> Results <p>The findings reveal that teacher support directly affects the school adaptation of urban adolescents and also indirectly influences it through the mediating role of resilience. Additionally, the left-behind status significantly moderates the direct effect of teacher relationship support on school adaptation among urban adolescents, but it does not similarly affect the direct impact of teacher academic support and emotional support.</p> Conclusions <p>Enhancing teacher support can effectively enhance the resilience of urban adolescents, leading to improved school adaptation. For left-behind adolescents, strengthening the quality of teacher-student relationships is particularly crucial for their school adaptation. Moreover, providing all students with consistent emotional support is essential, as it positively influences school adaptation regardless of their left-behind status.</p>